Every year I like to take a snapshot of Android platforms adoption for historical purposes. Below is the Android platform comparison 2015 vs. 2014. (Search my blog for previous ones).
Keeping track of platform adoption is important as it directly impacts what developers should be focusing on vs. what should be deprecating or end-of-life.
(Data source: Android Developer Dashboard)
Since 2014 we have Lollipop with its two API levels (21 and 22) with an overall 9.7% adoption rate. Ice Cream Sandwich went from 14.3% down to 5.3%. Jelly Bean decreased from 61.4% down to 39.2%, and KitKat jumped from 5.3% up to 39.8%.
Related to this see On Android and Fragmentation (early 2014).